Radiopaque suture package



May 25, 1965 R. L. TRAINER RADIOPAQUE SUTURE PACKAGE Filed April 18, 1962 INVENTOR. $926 01mm w 5. fwef United States Patent 3,185,299 RADIOPAQUE SUTURE PACKAGE Robert L Trainer, Fox River Grove, 111., assignor to The Kendall Company, Boston, Mass, a corporation of Massachusetts Filed Apr. 18, 1962, Ser. No. 188,468 Claims. (Cl. 206-633) This invention relates to plastic suture containers particularly to ligating containers or packages of the type which a surgeon may hold in the palm of his hand and from which he may dispense suture material as needed in tying off blood vessels and the like during an operation. Such containers may be simply formed from two sheets edge-sealed together or may comprise a one-piece molded cup. In each of these simple forms, the suture is retained by its resilient nature and is dispensed from a central hole. Ligating containers may be much more elaborate, however, comprising in one form a base mounting a molded rotatable circular reel from which the suture is drawn.

But whatever the form of such ligating packages, there has been reluctance on the part of some surgeons to use them. Most of this reluctance may be attributed to the fact that if ligating containers, of the type known prior to this invention, are inadvertently deposited in an open wound, they may remain undetected to cause post-operative complications long after the wound has otherwise healed.

Surgeons take elaborate precautions to insure that extraneous matter is not left in the wound. Surgical sponges, for instance, are carefully counted before and after use as are the various instruments used. Nevertheless, occasionally either a sponge or an instrument is left in a wound. The better practice is to make an X-ray photograph of the wound area both before and after the wound is closed so that if any instrument or sponge is left in the wound, it may be immediately removed. Surgical sponges are especially provided with radiopaque threads or grids so that the latter will be discernible in such X-ray photographs.

One of the objects of this invention is the provision of ligating containers which also are clearly detectable by X-ray photographic techniques.

Ligating containers are generally contained themselves in outer packages usually in the presence of tubing fluid solutions of various alcohols and water. Obviously, they must be removed from these outer packages before use, and for positive identification such ligating containers should be marked to indicate the type and size of contained suture. Most inks are attacked by tubing fluids, however, and any ink which is deposited on the suture is introduced into the body and may have a toxic eiiect. Some ligating package manufacturers have attempted to solve this problem by molding indicia upon the container. But unless expensive two-color molding is resorted to, the indicia are not readily discernible because of lack of contrast. Other ligating package manufacturers have used an additional printed layer so that the ink is segregated in its own sealed compartment between two layers of film.

An incidental object of this invention is the provision of an X-ray detectable ligating container which is clearly and contrastingly marked with identifying symbols without the use of ink.

The main object of this invention may be attained in one embodiment thereof by making a thermoplastic suture ligating container with at least one X-ray opaque panel as set forth herein. The incidental object of the invention may be attained in one embodiment thereof by cold embossing a pigmented panel which is X-ray opaque thereby producing clearly identifiable symbols by strain whitening of the plastic in the areas embossed.

In the drawings, FIGURE 1 represents an enlarged plan 'ice view of a typical radiopaque suture ligating package of this invention molded in one piece.

FIGURE 2 represents a cross-sectional view of the ligating package of FIGURE 1 taken along the line 2--2 viewed from the direction indicated by the arrows.

FIGURE 3 represents an enlarged plan view of a typical radiopaque suture ligating package of the type formed by heat-sealing two films together.

FIGURE 4 represents a cross-sectional view taken along the line 4-4 of FIGURE 3 viewed from the direction indicated by the arrows.

FIGURE 5 represents an enlarged plan view of a typical ligating suture package of the rotating reel type molded in two parts which snap together.

FIGURE 6 represents a cross-sectional view taken along the line 66 of FIGURE 5 viewed from the direction of the arrows. The preferred diameter of the suture ligating packages of this invention is between 1 /2 and 1% inches.

Probably the most useful and least expensive materials for molding and/ or heat seal forming of thermoplastic ligating containers of this invention are the alkylene polymers such as polyethylene, both high and low density, and polypropylene. Low density polyethylene, when filled with sufiicient X-ray opaque filler to make clear images on X-ray photographs, is satisfactory as a ligating container material but is rather low in film strength when the filler constitutes as much as 40% of the material. I have found that a mixture of high and low density polyethylene, with the former being /3 or more of the total resin, produces stronger and more attractive films when filled with 40% filler. For strongest films, the percentage of high density polyethylene should be increased as the filler is increased particularly if very thin films are to be utilized. Mixtures which are intended to be molded have somewhat less criticality in this respect than films.

Vlhile polyalkylenes are probably the preferred materials for the ligating containers of this invention, other thermoplastic film-forming and moldable polymers not attacked or appreciably swollen by water-alcohol solutions are suitable. The resins mentioned herein specifically are intended to be exemplary and do not indicate limitation of the invention thereto.

Thus vinyl resins including interpolymers and copolymers of vinyl acetate, vinyl chloride and vinylidene chloride and including Vinyl homopolymers excepting polyvinyl alcohol, polyvinyl acetate and polyvinyl butyral, each of which is attacked by alcohol, are suitable. Suitable also are various polyarnides, polystyrene and polyesters such as p lyalkylene terephthala-tes and polyurethanes which are not swollen by alcohol. The cellulose resins, due to their alcohol sensitivity are generally not suitable.

Plasticizers are generally not needed in the resins of the packages of this invention but, if used, they must qualify in the same respect as the resins. Non-migrating, particularly polymeric, plasticizers are preferred.

With regard to X-ray opaque material, while all elements, including the elements of the unfilled resin of which the ligating package is formed, have some degree of opacity, in the thicknesses of practical ligating packages, the resin alone when surrounded by human tissue is not discernible on X-ray photographs and hence the effect of differences in resins may for the most part be ignored.

In order to provide a clearly discernible X-ray image, therefore, the selected resin must be filled with a more opaque material. The filler material must be non-toxic and must have a solubility in alcohol and water solutions of less than 1 part in 1000 so that it will not be extracted by the suture tubing fluids. For X-ray contrast purposes as a practical matter and dictated by the practical limitations in package wall thickness and in concentration of filler in the resin mixture, a good rule of thumb is that at least half of the weight of the filler must be due to the presence of a chemical element in combined or in rare cases in free form having an atomic weight of 75 or more. Barium in the form of barium sulphate is the preferred X-ray opaque filler. Other compounds, mentioned by way of example and not in limitation, such as those of strontium, antimony, bismuth, mercury, tantalum, silver and gold in which the atomic weight of an element is at least 75 and which compounds have the requisite lack of solubility and toxicity, are suitable; thus, tantalum oxides, molybdenum sesquioxide, mercurous chloride, lead chrom'ate, silver chloride and tungsten trioxide among others may be used. Suitable likewise are some few elements themselves such as tantalum, silver and gold which have the requisite atomic weight and lack of toxicity and solubility.

, A more precise method of selection of filler percentages follows.

It has been found experimentally that barium sulphate, the preferred filler, when constituting 40% by weight of a layer of resin-filler mixture .008 inch thick, is barely discernible against animal flesh in an X-ray photograph. Obviously, the filled resin thickness couldbe in a single sheet or in several superimposed sheets. At any rate,-this barely discernible amount of barium sulphate is taken as a minimum for purposes of this invention.

Although the opacity and contrast properties of an element or a compound as displayed by X-ray photography may in some cases be calculated theoretically, as a practical matter it is far easier to determine the desired degree of'opacity and contrast by direct observation using empirical methods. For instance, if one wishes to determine the amount of barium sulphate per unit area for minimum opacity and contrast, the most practical method is to make up a thin uniform film containing a given small percentage of barium sulphate. For purposes of illustration let us assume that the film is two mils thick of which by weight is barium sulphate. A test panel is made up consisting of about rectangles of this film superimposed so that each rectangle projects about 4 inch beyond the rectangle immediately above it. 7 The rectangles are fastened together and the other edges are.

trimmed so as to be superimposed. The test panel is then X-ray photographed preferably when placed on or in a laboratory animal such as a rabbit. The area in which all twenty films are superimposed will be clearly discernible. The last film which isclearly discernible may be the sixteenth, This thickness (of the given film and those below it) has the desired minimum opacity. The minimum amount of barium sulphate per unit area is thus established as being approximately 10% by weight of a film 32 mils thick (16x2). Such thick films are undesirable, however, and so long as the amount of barium sulphate per unit area is undiminished, the film thickness may be reduced. Assuming we wish to use an 8 ml. film, the proper filler percentage by weight of the filled resin is determined as follows:

The above illustration is a practical means of determining the minimum X-ray opacity and contrast of a filler. Other step process methods may be utilized, of course. Obviously, one may refine the method explained to the point where differences between adjacent steps substantially disappear. For instance, one might, in a single exposure, use 80 rectangles of 1 mil film of which 5% by weight is the particular opaque filler. Because of the difficulties of size when all layers are in one test panel, however, it may be more convenient to use four panels exposed simultaneously. Panel one would contain twenty d film rectangles, each except the top film projecting A inch beyond the rectangle immediately above it. Panel two would contain films with the first 21 identical in size and films 21 to 39 projecting inch beyond the film immediately above it. Panel three would contain 60 films, the first 41 identical in size and films 41 to 59 projecting /1 inch beyond the film immediately above it. Panel four would contain 80 films, the first 61 identical in size and films 61 to 79 projecting beyond the film immediately above it. It is obvious that if 64 of such films (as with barium sulphate) must be superimposed to make the thickness discernible in .X-ray photographs, the difference in opacity and contrast caused by adding or subtracting a filrn from a panel is very slight indeed. Such critical determinationof the minimum thickness of film which becomes discernible on X-ray photographs is normally not required in practicing the invention. Rather one would a normally prefer a thickness from'the panel having some degree of opacity and contrast greater than the bare minimum.

As a rough guide in substituting another filler for barium sulphate, any filler which has a chemical element constituting more than of the filler weight which element has an atomic weight greater than 75 but less than that of barium will be required'in greater percentages than barium sulphate to provide the same degree 01 opacity. Likewise, any filler which has a chemical element constituting more than 50% of the filler weight which element has an atomic weight greater than that of barium may be used in smaller percentages than barium sulphate to provide the same degree of opacity. In any event, the empirical method explained above will permit selection of theprecise degree of opacity required.

resin. Pigments normally used for coloring such resins are entirely suitable. The thus pigmented filled resin presents a suitable contrast background for cold-embossing suitable indicia thereon. Most polymers when they are not plasticized to the extent'that they become rubbery will develop a permanent strain when distorted at room temperatures. This strain manifests itself in a whitening of the polymer where the strain occurs even though the polymer may be highly colored. In fact, when the polymer is highly colored, thecontrast is more vivid. In

producing the strain, any cold-embossing method may be Example I 7 Parts by weight Barium sulphate 51.3 High density polyethylene (Marlex 6009) 28.0

Low density polyethylene (Bakelite DDD4003) 20.7

To the above formula may be added .5 part of a whitener for polyethylene such as Stantone GPE-O and about 1.5 parts of a pigment for polyethylene such as Kohmstamm Blue #A98-29, if desired.

Referring once more to the drawings; in FIGURES 1 and 2, the suture ligating package 10 is molded in a single thin shell 11, open on the reverse side 17. The suture 13 is resiliently retained in the shell and has an end 14 protruding through a hole 12 in the front face 16. The shell 11 is formed of pigmented filled resin with the filler being X-ray opaque and present in such amounts as to render the shell discernible on an X-ray photograph.

On the front face, the letters chromic and 000 are formed of raised strain-whitened letters formed by cold-embossing the shell.

In FIGURES 3 and 4, the ligating package is formed of a front panel 21 and a back panel 27 heatsealed around the circumference in the area 23. The suture 23 is coiled inside the package and has an end 24 protruding from the hole 22. Areas 26 of the front panel are pigmented but the cold-embossed letters stand out in white relief. The front panel 21 preferably contains the X-ray opaque material whereas the back panel is preferably transparent or pigmented but the two panels may have the X-ray opaque filler distributed between them, if desired.

In FIGURES S and 6, the ligating package 30 is molded in two parts, a circular U-channeled reel portion 31 and a hub portion 37. The flange 39 on the hub passes through and snaps over the circular inner edge of the outer flange 36 of the reel, retaining the reel on the hub but free to rotate between flanges 39 and 40. The flange 40 carries an overhanging lip 38 which forms with the outer flange 36 of the reel an annular dispensing channel 32. The suture 33 is wound on the reel with an end projecting from the channel 32. While both the hub portion 37 and the reel 31 may contain X-ray opaque material, it is preferable to make one or the other X-ray opaque leaving the other either transparent or pigmented.

The reel illustrated is opaque and pigmented except where the letters are strain-whitened by cold-embossing but the embossing may be placed on the hub if that is desirable. Whichever portion of the package of FIGURE 5 contains X-ray opaque material, the total filled-resin thicknes (that is, the thickness of the two flanges of the reel if they contain X-ray opaque material or the two flanges of the hub if they contain X-ray opaque material or all four flanges if all contain X-ray opaque material) must contain sufficient X-ray opaque material to render the combined filled thickness discernible on an X-ray photograph.

The preferred method of mixing the tiller and the thermoplastic resin for use in containers of this invention is by hot milling the ingredients together. The hot mixture may be extruded, calendered or molded. Other wellknown mixing methods such as suspending the fiiler in a solvent solution of the thermoplastic resin or in a suspension of the thermoplastic resin followed by fusion of the resin by heat may be employed if desired, however.

I claim:

1. A container suitable as a dispenser for a suture in ligating including a structural element less than 60% by weight of polymeric material and more than by weight of a filler having a solubility in alcohol-Water solution of less than 1 part in 1000, said filler being a chemical compound rendering said structural element discern ible by X-ray photography, said polymeric material being selected from the group consisting of polyalkylenes other than low density polyethylene, blends of polyalkylenes other than low density polyethylene and blends of polyalkylenes including low density polyethylene in amounts or less by weight of each of said blends.

2. The container of claim 1 formed of at least two film panels heat-sealed to form an enclosure and a suture contained therein except for an end projecting from a hole in said container.

3. The container of claim 2 wherein at least one of the film panels is a structural element discernible by X-ray photography and at least one of the film panels is not.

4. The container of claim 1 molded to form a bowlshaped shell having an annular protruding mid-section defining an interior annular groove therein and having a centrally disposed hole in the bottom thereof, a surgical suture coiled in said groove with an end projecting from said hole.

5. The container of claim 1 wherein the structural element is a rotatable reel.

6. The container of claim 1 wherein the structural element is a hub upon which a suture dispensing reel is mounted in rotational relationship.

7. The container of claim 1 wherein the filler of said structural element contains a chemical element having an atomic weight of at least 75.

8. The container of clairnl wherein the filler of said structural element is barium sulphate.

9. The container of claim 1 wherein the tiller is barium sulphate and the polymeric material resin of said structural element is a mixture of high and low density polyethylene.

10. The container of claim 1 wherein the structural element includes a pigment and whereon markings, whitened by locally induced strains accompanying coldembossing of said structure, appear.

References Cited in the file of this patent UNITED STATES PATENTS 2,246,092 Gilman June 17, 1941 FOREIGN PATENTS 204,160 Australia Nov. 15, 1956 1,195,425 France May 19, 1959 1,238,904 France July 11, 1960 THERON E. CONDON, Primary Examiner.

EARLE J. DRUMMOND, GEORGE O. RALSTON,

Examiners. 

1. A CONTAINER SUITABLE AS A DISPENSER FOR A SUTURE IN LIGATING INCLUDING A STRUCTURAL ELEMENT LESS THAN 60% BY WEIGHT OF POLYMERIC MATERIAL AND MORE THAN 40% BY WEIGHT OF FILLER HAVING A SOLUBILITY IN ALCOHOL-WATER SOLUTION OF LESS THAN 1 PART IN 1000, SAID FILLER BEING A CHEMICAL COMPOUND RENDERING SAID STRUCTURAL ELEMENT DISCERNIBLE BY X-RAY PHOTOGRAPHY, SAID POLYMERIC MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF POLYALKYLENES OTHER THAN LOW DENSITY POLYETHYLENE, BLENDS OF POLYALKYLENES OTHER THAN LOW DENSITY OF POLYETHYLENE AND BLENDS OF POLYALKYLENES INCLUDING LOW DENSITY POLYETHYLENE IN AMOUNTS 2/3 OR LESS BY WEIGHT OF EACH OF SAID BLENDS. 